1. Field of the Invention
The present invention relates generally to a needle-less or needle-free hypodermic injection device, and particularly to such an injection device with a hand-held injector having a power unit which is pre-energized for the user of the device. A user of the hand-held injector device may pre-energize the power unit of the injector device by interfacing the device with a powered docking station. This powered docking station has a servo drive mechanism cooperating with the power unit to pre-energize it. Alternatively, the injection device may be pre-energized by use of a manual mechanism which employs the application of power provided by a human. For example, a human may step on a pedal of the manual pre-energizing mechanism in order to pre-energize the power unit of the hand-held injector.
The present invention also relates to a pre-filled, needle-free injection cartridge for use on such an injection device and which has features which prevent its unauthorized use for more than one injection.
2. Related Technology
Needle-less or needle-free hypodermic jet injection devices have been in commercial use for over 40 years. Initially hypodermic jet injectors were invented to expedite the process of injecting multiple patients in situations requiring that many injections be given in a short time, such as in a mass vaccination campaigns requiring numerous individuals to be injected with the same vaccine in a short time. In such uses, the same device was used to inject people serially, one person after another, so that a great number of people could be injected in a short time. In other words, such devices found wide application in mass vaccination and mass inoculation campaigns, and in the military, for example, to inoculate recruits. The related technology includes inventions such as: Ismach, U.S. Pat. No. 3,057,349; Isobe, U.S. Pat. No. 3,526,225; Mizzy, U.S. Pat. No. 3,859,996; and Landau, U.S. Pat. No. 4,266,541.
These inventions and devices for multiple use with many individuals are no longer considered safe. That is, with the wide-spread presence of HIV and Hepatitis B in the general population, the possibility of reflux of blood or body fluids into such an injection device, and subsequent the passing of virus or microorganisms to another individual who later receives an injection from the device clearly makes the risk of their use too great.
However, needle-less hypodermic jet injection devices for multiple use are still considered a safe and reliable means of delivery of certain medications, provided that all parts in contact with the fluid path are disposed of after each injection. That is, for devices that are meant to inject medication to different people, if the nozzle tip touches the patients"" skin, it is believed today by public health organizations that the possibility of transferring viruses such as HIV and Hepatitis B from one patient to another exists and may be significant. Further, it is believed that replacing only the nozzle tip after each injection is not sufficient to guarantee complete elimination of cross contamination between patients, because particles of blood or body fluid refluxed during the injection may carry viruses or pathogens to the dose chamber of the device. Therefore, this contamination of the device may contaminate the following medication dose to be injected in the next patient.
Accordingly, in case the same needle-less device is used on different patients, the only xe2x80x9cabsolutexe2x80x9d and acceptable methods to completely avoid cross contamination of diseases are either: a) sterilizing all parts in contact with the dose medication path after each injection, or; b) disposing of all parts in contact with the dose medication path after each injection. The first alternative is too time consuming, and is not practical in today""s health care industry because of cost considerations. The second alternative has also not proven to be cost effective for most vaccines and drugs commercially available in the marketplace and based on current technology.
On the other hand, there are needle-less injection devices that are meant to be used by a single patient in therapies that require frequent hypodermic injections of certain drugs to the same patient repeatedly. In other words, the hypodermic jet injection device is used repeatedly, but always on the same patient. Among these frequent, repetitive, and long term injectable drugs are insulin, human growth hormones, interferon for cancer treatment, drugs for migraine headaches, allergy reduction compounds, drugs for male erection dysfunction, injectable birth control drugs, and many others. Since these hypodermic injectable therapies are long term (i.e., some of them for the entire life of the patient), an individual patient may use a needle-less hypodermic jet injection device for a long period of time. That is, each needle-less hypodermic jet injection device is usually used and owned by only one person, in which case it is not medically justifiable for the parts in contact with each dose of medication to be sterilized or disposed of after each injection.
Another context in which needle-less jet injection devices may find application is in the clinical environment, particularly those in which clinic personnel give a rather large number of injections each day. In such uses, the components defining the dose medication path may be pre-filled with a medication, and after a single injection these components are disposed of. Alternatively, the components defining the dose medication path may he refillable, and may be used only on a single patient, although they are used repeatedly on this one patient. In each case, the needle-less hypodermic jet injection device (or injection power unit) will be used several times during a day""s treatment of patients, with the clinic personnel using the disposable or refillable components individually for each patient. It is generally accepted by official health institutions, including the U.S. Food and Drug Administration that if a needle-less hypodermic jet injection device is to be used daily by only one person, the injection head or the parts in contact the medicament dose will have to be cleaned and disinfected only once every 15 days.
The related technology includes some inventions such as: Fudge, U.S. Pat. No. 3,908,651; Lindmayer et al., U.S. Pat. No. 4,342,310; and Landau, U.S. Pat. No. 4,592,742, that describe devices that have a reusable or permanent injection head. These devices however, require the users to periodically disassemble the injection head for the necessary cleaning, unclogging and disinfecting. These procedures are time consuming and require a certain skill from the users.
In order to guarantee sterility, avoid the risk of cross contamination and reduce the user""s handling of the drug to be injected, in the recent years the concept of single-use disposable medicament dose has been brought to the needle-less hypodermic jet injection devices. The related technology contains several inventions that describe needle-less devices with disposable single-dose medicament containers or cartridges. Among these inventions are the ones in which the drug is pre-filled and the entire needle-less device is single-use and disposed of after each injection, such as: Parsons, U.S. Pat. No. 4,913,699; Alchas et al., U.S. Pat. No. 5,334,144; and Weston, WO 95/03844.
Other inventions such as: Landau, U.S. Pat. No. 4,966,581; Dunlop, U.S. Pat. No. 5,062,830; and Edwards, U.S. Pat. No. 5,063,165, disclose devices in which the entire device is disposed of after a single use. These devices adequately meet the safety concerns of preventing the spread of disease, but are unacceptably expensive because of the disposal of the device after a single use.
McKinnon, U.S. Pat. No. 5,312,335, describes a device that comprises a needle-less syringe that may be filled manually by the user, outside the gas-powered unit. McKinnon""s needle-less syringe is also designed to be single-use as, once a single injection is over, the syringe has to be necessarily removed from the gas powered unit.
These inventions comprising disposable single-use needle-less hypodermic jet injection devices, or needle-less devices that utilize single-use disposable medicament cartridges, have a number of limitations standing in the way of their wide individual and commercial uses. One of these limitations is the difficulty, time, or expense involved in re-cocking or re-energizing the injection units preparatory to the next injection. Some units require the user to have considerable hand strength in order to manipulate the unit and re-cock it. Others require good eye sight in order to assess when the unit is re-energized with a sufficient level of energy for the next injection to be given.
Some of these conventional needle-less hypodermic jet injection devices make use of hydraulic power to cock the injection device, or to energize the injection device preparatory to making of an injection. Others of these devices make use of an internal spring and cocking or energizing mechanism which is contained within the injection device itself. These devices which have the energizing or cocking mechanism within the injection device are necessarily somewhat larger and heavier than would be the case were the energizing device to be located elsewhere.
In view of the above, it would be desirable and is an object for this invention to provide a needle-less hypodermic jet injection device which includes a pre-filled, single use injection cartridge.
Another object for this invention is to provide a needle-less hypodermic jet injection system which includes a hand-held injection device or injector part which is pre-energized and carries an injection cartridge with medication cylinder, injection nozzle, and injection ram; and which makes use of a separate component of the system to energize the hand piece injector. Still another object for this invention is to provide such a needle-less hypodermic jet injector device which includes an injection hand piece powering the injection cartridge, and which hand piece is quickly re-energized by interfacing the hand piece with a cocking or energizing mechanism. Additionally, it is an object to provide such a needle-less injection device which allows the hand piece to be re-energized by interfacing the hand piece with, for example, a motor-driven re-energizing mechanism, or with a human-powered (i.e., manually or with a pedal, for example) re-energizing mechanism.
In some respects like the single-use needle-less injection devices, this injection system also utilizes an injection head or cartridge which in the present case is made of materials of relatively low cost and good mechanical performance. Preferably, these components of the injection cartridge are made of thermoplastics. But, unlike the older single-cartridge, multiple-use, multiple-recipient devices, and unlike the single-use devices, this invention provides the design features and elements to allow the injection cartridge to be easily refilled and reused by an authorized user who can refill the injection cartridge with the proper amount of medication for each injection.
On the other hand, unlike the reusable needle-less injection devices which require disassembly, cleaning and disinfecting every 15 days, this invention in one embodiment provides the users with the means to easily, quickly and economically remove the injection cartridge, discard it, and replace it with a new one, every 15 days.
So to, the present invention provides features allowing the injection cartridge in an alternative embodiment to be manufactured as a single-use unit; which cannot easily be refilled and reused by the user who is not authorized to do so.
A needle-less hypodermic jet injection system embodying this invention includes, for example: a hand-held injector carrying an injection cartridge with medication cylinder, injection nozzle, and injection ram; the hand-held injector including a power unit which is pre-energized prior to each injection; and a trigger mechanism allowing the energy stored in the power unit to be released and applied in driving the injection ram to cause the injection; and an energizing mechanism with which the hand-held injector interfaces to either be re-energized automatically or by the application of force and displacement applied by a person.